Naturally, results from human studies are more applicabel to the human population than animal studies. Still,large enough numbers must be used in the studied to make the results generalizable to the entire population, and the sample group needs to be representative of the population of interest.

Human nutrition research can be particularly challenging because of individual differences (heck, you can ORDER a genetically pure strain of rat, but you can't do that when it comes to human subjects!), the many confounding factors that may influence results, the difficulty esitmating nurient intake, and the difficulty gettin people to adhere to a study dietary regimen. Human studies must be planned, designed, and contolled very carefully to ensure meaningful (reliable and valid) results.

General types of human studies include:

• Basic Science Research
• Descriptive Studies
• Epidemiological Studies
• Clinical Trials
• Quasi-experimental studies
• Qualitative studies

Information about each of the above types of human studies is detailed in subsequent pages, and you can access the the Royal Windsor Society for Nursing Research website for more information on types of research and study design.